Question
Hi, we have 4 or 5 willow tress and this year they have Willow Leaf Beetles.  First time I have noticed them and we have been here since 1988....I read in your answer to a question about them what to use to spray them with but that would be pretty much impossible to do on our own due to the height of the trees....will they go away on their own or will they be coming back every year now since your article mentioned they lay eggs on the leafs?...If we do not do anything will they kill the willow trees?..we live in Michigan.  Thanks

Answer
If the tree is too tall to spray with liquids I would use Bayer Advanced Tree and Shrub Insect Control insecticide. This is applied to the soil around the tree and the roots will carry it to the leaves and when the beetles feed they will be killed. It is not fast acting so results may take several weeks to show up depending on the rainfall or the amount of water to move the insecticide. One application will protect the tree for the year. Here is a web link to this product check with your local garden type store for it. http://www.bayeradvanced.com/tree-shrub-care/products/12-month-tree-shrub-insect...

They will not kill the tree but if they defoliate the tree for a couple of times the tree will be weakened and lose some growth. When they complete a life cycle the beetles will disappear but will usually have 2-4 generations per year so expect the tree to try to leaf out again and the beetles will hatch out a new generation to defoliate the tree. The Bayer product will protect the tree from the other generations feeding on the leaves.